<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.1/jquery.js"></script>
    <script>
        var cat = jQuery.extend(true,{},{a:1},{b:23,c:[{cd:12}]});//深拷贝
        var box = jQuery(".box");
        console.log(cat);
        // jQuery.fn.extend({
        //     callCat:function(){
        //         console.log(this);
        //     }
        // })
        jQuery.fn.callCat = function(){
            console.log(this);
        }
        box.callCat();
        box.extend(true,cat);
        console.log(box);
        box.map(function(index,item){
            console.log(item);
        })
    </script>
</body>
</html>